The present invention provides a coupling for joining a pair of shafts disposed head to head, said coupling being shaped as to work without any inconvenience even in the case that the shafts linked thereto are somewhat off-centered.
The coupling according to the invention, moreover, consists of fewer components, is easier to assemble and requires reduced maintenance, than known devices.
There are known different types of coupling for linking a pair of shafts arranged head-to-head, even if they are slightly off-centered.
For instance, rubber pin couplings are known, consisting substantially of a pair of flanges with a hub keyed at the shaft ends, on which are cantilever-mounted a series of alternate pins covered with tubular rubber elements, engaging with corresponding holes made in the flanges.
This kind of coupling, however, enables just a limited off-centering of the shafts, and is prone to wear owing to the deterioration in time of the rubber covering of the pins.
Other couplings, for instance those of the Falk type, comprise a pair of disks with hubs keyed on the shaft ends, said disks being provided with a plurality of protruding elements linked to one another by a flexible metal belt, enabling limited reciprocal shifting of the two parts of which the coupling consists.
This embodiment too allows only limited off-centering, and is very expensive, owing to its complex structure.
There are known also claw couplings wherein the hubs fixed to the two shafts are provided with peripheral teeth that engage with corresponding inner teeth of a bell-like device that joins the two hubs together. These teeth may have a rounded outline, so as to allow the shafts to be slightly off-centered, up to about 2.degree.-3.degree. at the most.
This kind of coupling too, however, is not free of drawbacks, both because the making of teeth with a rounded profile is a rather costly process and because the friction among the coupling parts makes the coupling itself wear out and reduces the life-time thereof.